Backlight unit with heat dissipating member and liquid crystal display device including the same

ABSTRACT

A backlight unit includes: a light source which generates a light; a printed circuit board on which the light source is mounted; and a lower frame in which the light source and the printed circuit board are accommodated The lower frame includes: a bottom portion having a planar shape; and a side wall portion bent from an edge of the bottom portion to extend therefrom. The side wall portion defines an aperture at the edge of the bottom portion, the printed circuit board is disposed at the aperture defined by the side wall portion of the lower frame, and a portion of the printed circuit board disposed at the aperture is exposed to outside the backlight unit.

This application claims priority to Korean Patent Application No.10-2015-0061130, filed on Apr. 30, 2015, and all the benefits accruingtherefrom under 35 U.S.C. §119, the disclosure of which is incorporatedherein in its entirety by reference.

BACKGROUND

1. Field

Exemplary embodiments of the invention relate to a backlight unit and aliquid crystal display (“LCD”) device including the same, and moreparticularly, to a backlight unit having enhanced heat dissipationefficiency and an LCD device including the same.

2. Description of the Related Art

Display devices are classified into types including liquid crystaldisplay (“LCD”) devices, organic light emitting diode (“OLED”) displaydevices, plasma display panel (“PDP”) devices, electrophoretic display(“EPD”) devices, and the like, based on a light emitting scheme thereof.

An LCD device is a passive-matrix light emitting device including adisplay panel and a backlight unit generating and providing light to thedisplay panel. Such an LCD device includes two opposing display panelsubstrates, electrodes respectively disposed in the two display panelsubstrates, and a liquid crystal layer interposed between the displaypanel substrates. In an LCD device, orientations of liquid crystalmolecules of the liquid crystal layer are rearranged upon voltages beingapplied to the electrodes, and thereby the amount of light emitted froma backlight unit is adjusted in the LCD device.

A backlight unit is classified into types including a direct-typebacklight unit, an edge-type backlight unit, a corner-type backlightunit and the like, based on a position of a light source within thebacklight unit. In a direct-type backlight unit, a plurality of lightsources are disposed below and overlapping a display panel, and lightemitted from the light source is irradiated toward the display panelthrough a diffusion plate of the backlight unit. An edge-type backlightunit includes a light guide plate and light sources which are arrangedat a side of the light guide plate of the backlight unit, and lightemitted laterally from the light source is irradiated toward a displaypanel through the light guide plate.

A light source used in a backlight unit includes a point light source,such as a light emitting diode (“LED”). Since more than about 70% toabout 80% of power input to an LED is converted into thermal energy,heat dissipation efficiency may be key to the LED development. Inparticular, a temperature rise of an LED due to such heat is directlyassociated with a decrease in light efficiency of the backlight unitincluding the light source. Accordingly, enhancing heat dissipationefficiency of the backlight unit may be essential in order to reduce oreffectively prevent the deterioration of a light source and to enhancean overall performance of an LCD device including the light source.

SUMMARY

One or more exemplary embodiments of the invention are directed to abacklight unit having enhanced heat dissipation efficiency and a liquidcrystal display (“LCD”) device including the same.

According to an exemplary embodiment of the invention, a backlight unitincludes: a light source which generates a light; a printed circuitboard (“PCB”) on which the light source is mounted; and a lower frame inwhich the light source and the printed circuit board are accommodated.The lower frame includes: a bottom portion having a planar shape; and aside wall portion bent from an edge of the bottom portion to extendtherefrom. The side wall portion defines an aperture at the edge of thebottom portion, the printed circuit board is disposed at the aperturedefined by the side wall portion of the lower frame, and a portion ofthe printed circuit board disposed at the aperture is exposed outsidethe backlight unit.

The aperture may have a substantially same area as that of a surface ofthe printed circuit board which is disposed at the aperture.

The light source may be a light emitting diode (“LED”).

The printed circuit board may be one of a metal printed circuit board(“MPCB”) and a metal core printed circuit board (“MCPCB”).

The printed circuit board may include at least one of stainless steel,aluminum, an aluminum alloy, magnesium, a magnesium alloy, copper, acopper alloy and an electro-galvanized steel sheet.

The printed circuit board which is disposed at the aperture may becoupled to the bottom portion and heat may be transferred between theprinted circuit board and the bottom portion coupled to each other.

The printed circuit board which is disposed at the aperture may bescrew-coupled to the bottom portion and the heat may be transferredbetween the printed circuit board and the bottom portion screw-coupledto each other.

The backlight unit may further include a light source unit includingtherein: the light sourced which generates the light, the printedcircuit board which is disposed at the aperture, and an insulating layerbetween the light source and the printed circuit board.

The printed circuit board may have a thickness in a range of about 0.5millimeters (mm) to about 3.0 millimeters (mm).

The backlight unit may further include a heat-dissipating extrusion barcoupled to the printed circuit board which is disposed at the aperture.Heat may be transferred between the heat-dissipating extrusion bar andthe printed circuit board coupled to each other, and theheat-dissipating extrusion bar may be disposed above the light source.

The heat-dissipating extrusion bar may be screw-coupled to the printedcircuit board which is disposed at the aperture and the heat may betransferred between the heat-dissipating extrusion bar and the printedcircuit board screw-coupled to each other.

The heat-dissipating extrusion bar may include at least one of stainlesssteel, aluminum, an aluminum alloy, magnesium, a magnesium alloy,copper, a copper alloy and an electro-galvanized steel sheet.

The backlight unit may further include a heat-dissipating tape attachedto a surface of the printed circuit board which is disposed at theaperture, the surface of the printed circuit board to which theheat-dissipating tape is attached being exposed outside the backlightunit.

The heat-dissipating tape may define a microcavity structure.

According to another exemplary embodiment of the invention, a liquidcrystal display (“LCD”) device includes: a display panel which displaysan image using a light; and a backlight unit which provides the light tothe display panel. The backlight unit includes: a light source whichgenerates and provides the light; a printed circuit board (“PCB”) onwhich the light source is mounted; and a lower frame in which thedisplay panel, the light source and the printed circuit board areaccommodated. The lower frame includes: a bottom portion having a planarshape; and a side wall portion bent from an edge of the bottom portionto extend therefrom. The side wall portion defines an aperture at theedge of the bottom portion, the printed circuit board is disposed at theaperture defined by the side wall portion of the lower frame, and aportion of the printed circuit bard disposed at the aperture is exposedoutside the backlight unit.

The aperture may have a substantially same area as that of a surface ofthe printed circuit board which is disposed at the aperture.

The printed circuit board which is disposed at the aperture may becoupled to the bottom portion, and heat may be transferred between theprinted circuit board and the bottom portion coupled to each other.

The liquid crystal display device may further include a heat-dissipatingextrusion bar coupled to the printed circuit board which is disposed atthe aperture. Heat may be transferred between the heat-dissipatingextrusion bar and the printed circuit board coupled to each other, andthe heat-dissipating extrusion bar coupled to the printed circuit boardmay be disposed above the light source.

The heat-dissipating extrusion bar may define a support portion thereofwhich supports the display panel thereon.

The liquid crystal display device may further include a heat-dissipatingtape attached to a surface of the printed circuit board which isdisposed at the aperture, the surface of the printed circuit board towhich the heat-dissipating tape is attached being exposed outside thebacklight unit.

According to one or more exemplary embodiments, the backlight unit withone or more heat dissipating members and the LCD device including thesame may enhance heat dissipation efficiency by a metal-material PCBhaving relatively high thermal conductivity and having a predeterminedthickness, and by exposing the highly thermally conductive PCB directlyto an external environment relative to the backlight unit.

In addition, the backlight unit with one or more heat dissipatingmembers and the LCD device including the same may enhance heatdissipation efficiency by thermally contacting the PCB, on which thelight source is mounted, to the metal frame (e.g., a lower frame, aextrusion bar, etc.) which accommodates the respective components of theLCD device therein.

Further, the backlight unit with one or more heat dissipating membersand the LCD device including the same may include the heat-dissipatingtape as a heat dissipating member, where the heat-dissipating tape hasthe microcavity structure and the microcavity-structure heat-dissipatingtape is disposed on the externally exposed portion of the PCB on whichthe light source is mounted.

The foregoing is illustrative only and is not intended to be in any waylimiting. In addition to the illustrative embodiments, and featuresdescribed above, further embodiments, and features will become apparentby reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure of invention willbe more clearly understood from the following detailed description takenin conjunction with the accompanying drawings, in which:

FIG. 1 is an exploded perspective view illustrating an exemplaryembodiment of a liquid crystal display (“LCD”) device according to theinvention;

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1;

FIG. 3 is a perspective view illustrating an exemplary embodiment of anextrusion bar according to the invention;

FIG. 4 is an enlarged electron-microscope image depicting an exemplaryembodiment of a portion of a heat dissipation tape according to theinvention;

FIG. 5A is an exploded perspective view schematically illustrating anexemplary embodiment of a backlight unit according to the invention;

FIG. 5B is a perspective view illustrating an assembled state of thebacklight unit of FIG. 5A;

FIG. 6A is an exploded perspective view schematically illustratinganother exemplary embodiment of a backlight unit according to theinvention;

FIG. 6B is a perspective view illustrating an assembled state of thebacklight unit of FIG. 6A; and

FIG. 7 is a cross-sectional view schematically illustrating a path ofheat generated in a light source of an exemplary embodiment of abacklight unit according to the invention.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully hereinafter withreference to the accompanying drawings.

However, the invention may be embodied in different forms and should notbe construed as limited to the exemplary embodiments set forth herein.Rather, these exemplary embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey exemplaryimplementations to those skilled in the art.

Throughout the specification, when an element is referred to as being“connected” to another element, the element is “physically connected” tothe other element or “electrically connected” to the other element withone or more intervening elements interposed therebetween. When anelement is referred to as being “directly connected” to another element,the element is “directly physically connected” to the other element or“directly electrically connected” to the other element with nointervening elements interposed therebetween.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

It will be understood that, although the terms “first,” “second,” andthe like, may be used herein to describe various elements, components,areas, layers and/or sections, these elements, components, areas, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, area, layer or sectionfrom another element, component, area, layer or section. Thus, a firstelement, component, area, layer or section discussed below could betermed a second element, component, area, layer or section withoutdeparting from the teachings of exemplary embodiments.

When it is determined that a detailed description may make the purposeof the invention unnecessarily ambiguous in the description of theinvention, such a detailed description will be omitted. In addition, thesame components and corresponding components are given the samereference numeral.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Hereinafter, exemplary embodiments of a display device according to theinvention are explained with respect to a liquid crystal display (“LCD”)device including an edge-type backlight unit, but the invention is notlimited thereto.

FIG. 1 is an exploded perspective view illustrating an exemplaryembodiment of an LCD device 100 according to the invention. FIG. 2 is across-sectional view taken along line I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, the LCD device 100 includes a display panel110, an intermediate frame 120, an extrusion bar 130, an optical sheet140, a light guide plate 150, a light source unit 160, a heatdissipation sheet such as a heat dissipation tape 170, a reflectivesheet 180, a lower frame 190 and the like.

As used herein, the intermediate frame 120, the extrusion bar 130, theoptical sheet 140, the light guide plate 150, the light source unit 160,the heat dissipation tape 170, the reflective sheet 180, the lower frame190 and the like, are collectively referred to as a backlight unit.

The display panel 110 may be provided in a quadrangular planar shape anddisplays an image by receiving an externally applied electric signal.The display panel 110 may include a first display substrate 111, asecond display substrate 113 opposing the first display substrate 111,and a liquid crystal layer (not illustrated) between the first andsecond display substrates 111 and 113.

The first display substrate 111 may include a plurality of pixelelectrodes arranged in a matrix form on a first base substrate, a thinfilm transistor applying a driving voltage to each of the pixelelectrodes on the first base substrate, and various signal lines fordriving the pixel electrode and the thin film transistor on the firstbase substrate.

The second display substrate 113 may be disposed to oppose the firstdisplay substrate 111, and may include a common electrode including orformed of a transparent conductive material, and a color filter, on asecond base substrate. The color filter may include red, green and bluecolor filters, by way of example, but the invention is not limitedthereto.

The liquid crystal layer (not illustrated) may be interposed between thefirst and second display substrates 111 and 113, and orientations ofliquid crystal molecules of the liquid crystal layer may be rearrangedby an electric field formed between the pixel electrode and the commonelectrode. The rearranged liquid crystal layer may adjust a level oftransmittance of light emitted from the backlight unit, the light havingthe adjusted level of transmittance may be transmitted through the colorfilter, and an image may be displayed outwardly at a viewing side of theLCD device 100.

A lower polarizing plate 111 a and an upper polarizing plate 113 a mayfurther be disposed on a lower surface of the first display substrate111 and an upper surface of the second display substrate 113,respectively. The upper polarizing plate 113 a and the lower polarizingplate 111 a may each have a planar area corresponding to a planar areaof the display panel 110 in size.

The upper polarizing plate 113 a may allow a predetermined component ofpolarized light from among externally supplied light to passtherethrough, and may absorb or block the remainder of the externallysupplied light. The lower polarizing plate 111 a may allow apredetermined component of polarized light from among the light emittedfrom the backlight unit to pass therethrough, and may absorb or blockthe remainder of the light emitted from the backlight unit.

A driving circuit board 115 may be disposed laterally of at least oneside of the display panel 110. The driving circuit board 115 may providevarious control signals and power signals to the display panel 110 fordriving the display panel 110.

The display panel 110 and the driving circuit board 115 may beelectrically connected to one another by at least one flexible printedcircuit board (“FPCB”) 117. The FPCB 117 may be a chip-on-film (“COF”)structure or a tape-carrier-package (“TCP”) structure, and the number ofFPCBs 117 may vary based on, for example, a size and a driving scheme,of the display panel 110.

A driving chip 119 may be mounted on the FPCB 117. The driving chip 119may generate various driving signals for driving the display panel 110.The driving chip 119 may be a single chip in which a timing controllerand a data driving circuit are integrated with one another, and may alsobe referred to as, for example, a driver integrated circuit (“IC”) or asource integrated circuit (“IC”).

The intermediate frame 120 may support a lower edge of the display panel110, and may define a space in which the optical sheet 140, the lightguide plate 150, the light source unit 160, the reflective sheet 180 andthe like are accommodated.

The intermediate frame 120 may have a polygonal frame shape to define anopening therein. In an exemplary embodiment, for example, theintermediate frame 120 may have an overall quadrangular frame shapewhich defines an opening therein. The intermediate frame 120 may beprovided as a single, unitary frame, or alternatively, may be formed bya plurality of divided portions. In the exemplary embodiment, theintermediate frame 120 may have a polygonal frame shape in which atleast a side thereof at which the light source unit 160 is disposed isomitted.

The intermediate frame 120 may include at least one of an epoxy resincomposition; a silicon resin composition; a modified epoxy resincomposition such as a silicon-modified epoxy resin; a modified siliconresin composition such as an epoxy-modified silicon resin; a polyimideresin composition; a modified polyimide resin composition;polyphthalamide (“PPA”); a polycarbonate (“PC”) resin; polyphenylenesulfide (“PPS”); a liquid crystal polymer (“LCP”); an acrylonitrilebutadiene styrene (“ABS”) resin; a phenol resin; an acrylic resin; and apolybutylene terephthalate (“PBT”) resin.

FIG. 3 is a perspective view illustrating an exemplary embodiment of anextrusion bar according to the invention.

Referring to FIGS. 1, 2 and 3, the extrusion bar 130 may externallydissipate heat generated in the light source unit 160, and may support alower edge of the display panel 110. Where the intermediate frame 120has the polygonal frame shape in which a side thereof at which the lightsource unit 160 is disposed is omitted, the extrusion bar 130 maysupport the lower edge of the display panel 110 at the side at which thelight source unit 160.

The extrusion bar 130 may define a fixing portion 131 which is coupledto a printed circuit board (“PCB”) 163 of the light source unit 160, anda support portion 133 extending from the fixing portion 131 andsupporting the lower edge of the display panel 110. The extrusion bar130 may be screw-coupled to the PCB 163, but the invention is notlimited thereto. In exemplary embodiments, the shape of the extrusionbar 130 is not limited there above-described structure, and theextrusion bar 130 may have various shapes. The PCB 163 may contact theextrusion bar 130 to transfer heat therebetween, but the invention isnot limited thereto.

The extrusion bar 130 may include a metal having a relatively highthermal conductivity, for example, at least one of stainless steel,aluminum (Al), an Al alloy, magnesium (Mg), a magnesium (Mg) alloy,copper (Cu), a copper (Cu) alloy and an electro-galvanized steel sheet.

A buffer 135 may be disposed on a lower surface of the fixing portion131. A fixing member such as an adhesive 137 which fixes the displaypanel 110 relative to the extrusion bar 130 may further be disposed onan upper surface of the support portion 133 of the extrusion bar 130.

Referring to FIGS. 1 and 2, the optical sheet 140 may be disposed on thelight guide plate 150, and may serve to diffuse or collimate lighttransmitted from the light guide plate 150. The optical sheet 140 maycollectively include a diffusion sheet, a prism sheet and a protectivesheet. The diffusion sheet, the prism sheet and the protective sheet maybe sequentially stacked on the light guide plate 150.

The prism sheet may collimate light guided and emitted by the lightguide plate 150, the diffusion sheet may diffuse light collimated by theprism sheet, and the protective sheet may protect the prism sheet. Lighthaving passed through the protective sheet may be supplied to thedisplay panel 110.

The light guide plate 150 may uniformly supply light, emitted laterallyfrom the light source unit 160, to the display panel 110. The lightguide plate 150 may have a quadrangular planar shape. According toembodiments, the light guide plate 150 may have various shapesincluding, for example, a predetermined groove or a protrusion, based ona position of a light source.

The light guide plate 150 is described herein as having a planar shape,that is, a plate, for ease of description. While the light guide plate150 is described as a plate, such as having a relatively largecross-sectional thickness for ease of description, the invention is notlimited thereto. According to embodiments, the light guide plate 150 maybe provided in a sheet or film shape for which the cross-sectionalthickness is smaller than that of the plate and is relatively small ascompared to the planar size thereof, to achieve slimness of the displaydevice. The light guide plate 150 is to be understood as having aconcept that includes not only a plate but also a film which guideslight provided from the light source unit 160.

The light guide plate 150 may include or be formed of alight-transmissive material, for example, an acrylic resin such aspoly(methyl methacrylate) (“PMMA”) or polycarbonate (“PC”) to help guidelight efficiently.

The light source unit 160 may include a light source 161 and the PCB 163on which the light source 161 is mounted.

The light source 161 may be disposed at an edge or a light-incident sidesurface of the light guide plate 150. In other words, the light source161 may emit light at least laterally toward the edge or thelight-incident side surface of the light guide plate 150. The lightsource 161 may include a light emitting diode (“LED”) or an LED chip. Inan exemplary embodiment, for example, the light source 161 may be agallium nitride (GaN)-based LED which generates and emits blue light. Aplurality of light sources 161 may be arranged along a length of the PCB163. The number of the light sources 161 in the light source unit 160may vary based on, for example, a size and luminance uniformity, of thedisplay panel 110.

The PCB 163 may be one of a metal printed circuit board (“MPCB”) and ametal core printed circuit board (“MCPCB”). The PCB 163 may have a barshape, having a relatively large length compared to a width thereof,defining an upper surface, a lower surface and side surfaces thereof.The PCB 163 may include a metal material having a relatively highthermal conductivity, for example, at least one of stainless steel,aluminum (Al), an Al alloy, magnesium (Mg), a magnesium (Mg) alloy,copper (Cu), a copper (Cu) alloy and an electro-galvanized steel sheet.A detailed description pertaining to the PCB 163 will be providedfurther below.

In the exemplary embodiment of the LCD device 100 according to theinvention, a portion of the PCB 163 is exposed external to the lowerframe 190, to thereby relatively rapidly dissipate high-temperature heatoutwards from the LCD device 100 and the backlight unit thereof, whichis generated from the light source 161.

In addition, an insulating layer 162 may further be disposed between thelight source 161 and the PCB 163 including or formed of a metal.

The light source unit 160 may be disposed at one, two or four sidesurfaces of the light guide plate 150 based on, for example, a size andluminance uniformity, of the display panel 110. In other words, thelight source unit 160 may be disposed at one or more edges of the lightguide plate 150.

Although not illustrated in FIGS. 1 and 2, a wavelength converting unit(not illustrated) may be interposed between the light guide plate 150and the light source unit 160. The wavelength converting unit mayinclude a material which converts a wavelength of light provided theretoby the light source unit 160. In an exemplary embodiment, for example,the wavelength converting unit may convert a wavelength of blue lightemitted from a blue LED light source to provide white light therefrom.

The heat dissipation tape 170 may be disposed on at least a surface ofthe PCB 163 of the light source unit 160. In particular, the heatdissipation tape 170 may be disposed on an outwardly-exposed surface ofthe PCB 163 which is exposed externally from the intermediate and lowerframes 120 and 130.

FIG. 4 is an enlarged electron-microscope image depicting an exemplaryembodiment of a portion of a heat dissipation tape according to theinvention.

Referring to FIG. 4, the heat dissipation tape 170 may have amicrocavity structure. The microcavity structure may include a pluralityof micrometer-sized holes defined therein and are arranged in a regularmanner along a plan view of the heat dissipation tape 170. The heatdissipation tape 170 may enhance heat dissipation efficiency based on asurface plasmon resonance phenomenon.

A surface plasmon is a type of electromagnetic wave generated on a metalsurface including a light component. Surface plasmon resonance refers toa process in which a surface plasmon propagating along a metal surfaceis externally extracted using a microstructure or a nanostructure havingthe same wavelength as that of the surface plasmon which occurs on themetal surface.

Due to a heat generated in the light source 161, an infrared (“IR”)light or a light from thermal radiation within a range of about 10micrometers (μm) may be generated on a surface of the PCB 163 includingor formed of a metal. The heat dissipation tape 170 may externally emitthe infrared light or the light from thermal radiation which isgenerated on the surface of the PCB 163, using the microcavity structuredefined therein.

The heat dissipation tape 170 may increase emissivity of the infraredlight generated on the surface of the PCB 163, thereby significantlyenhancing radiant heat dissipation efficiency.

Referring to FIGS. 1 and 2, the reflective sheet 180 may include or beformed of, for example, polyethylene terephthalate (“PET”) to havereflectivity. One surface of the reflective sheet 180 may be coated witha diffusion layer containing, for example, titanium dioxide (TiO₂). Thereflective sheet 180 may include or be formed of a material containing ametal, such as silver (Ag).

The lower frame 190 may maintain an overall framework of the LCD displaydevice 100, and may protect various components accommodated therein. Thelower frame 190 may define a bottom portion 191 and a side wall portion193 which is bent from the bottom portion 191 to extend therefrom.

The side wall portion 193 may define an aperture 193 h through which aportion of the PCB 163 is exposed outside the backlight unit. In anexemplary embodiment, for example, the aperture 193 h may havesubstantially the same planar area as that of a surface of the PCB 163.In other words, in an exemplary embodiment, the lower frame 190 may havea shape in which a portion of the side wall portion 193 at which thelight source unit 160 is positioned is omitted.

The lower frame 190 may include or be formed of a metal material havingrigidity and relatively excellent heat dissipation properties. In anexemplary embodiment, for example, the lower frame 190 may include atleast one of stainless steel, aluminum (Al), an Al alloy, magnesium(Mg), a Mg alloy, copper (Cu), a Cu alloy and an electro-galvanizedsteel sheet.

FIG. 5A is an exploded perspective view schematically illustrating anexemplary embodiment of a backlight unit according to the invention.FIG. 5B is a perspective view illustrating an assembled state of thebacklight unit of FIG. 5A.

Referring to FIGS. 5A and 5B, the PCB 163 may have a bar shape whichdefines an upper surface 163 a, a lower surface 163 b, and side surfaces163 c and 163 d of the PCB 163. At least one light source 161 may bemounted on one side surface 163 c among the side surfaces 163 c and 163d of the PCB 163. Referring to FIGS. 5A and 5B, although an insulatinglayer is not shown separate from a light source, the feature labeled 161may be considered as representing an insulating layer within 161 andadjacent to the side surface 163 c of the PCB 163 so as to be disposedbetween a light source within 161 and the PCB 163.

The PCB 163 may be one of a metal printed circuit board (“MPCB”) and ametal core printed circuit board (“MCPCB”), and may have a thickness “t”in a range of about 0.5 millimeter (mm) to about 3.0 millimeters (mm).

A length of the PCB 163 may be coupled to and extend along an edge ofthe lower frame 190 (refer to FIG. 1). In particular, the lower surface163 b of the PCB 163 and the bottom portion 191 of the lower frame 190may be coupled to each other such as by being screw-coupled to eachother. The bottom portion 191 of the lower frame 190 may have aquadrangular planar shape and the side wall portion 193 is bent upwardlyfrom an edge of the bottom portion 191 to extend therefrom. The PCB 163may contact the lower frame 190 to transfer heat therebetween, but theinvention is not limited thereto. In the exemplary embodiment of the LCDdevice 100 according to the invention, a portion of the side wallportion 193 at a side of the lower frame 190 at which the PCB 163 isdisposed may be omitted.

Accordingly, at least a portion of the PCB 163, for example, the otherside surface 163 d among the side surfaces 163 c and 163 d of the PCB163 opposing the one side surface 163 c on which the light source 161 ismounted, may be exposed externally with respect to the lower frame 190.

The light source 161 may be a light generating and emitting element, andtemperature thereof may rapidly increase over the course of usage time.In this regard, the exemplary embodiment of the LCD device 100 accordingto the invention may form the PCB 163, on which the light source 161 ismounted, using a metal material having a predetermined thickness “t”,and may dispose a portion of the PCB 163 to be exposed directly to anexternal environment relative to components of the backlight unit,thereby relatively rapidly dissipating high-temperature heat generatedin the light source 161.

In addition, the exemplary embodiment of the LCD device 100 according tothe invention may further include the extrusion bar 130 coupled to thePCB 163 to be disposed above the light source 161, where the extrusionbar 130 also externally dissipates heat generated in the light sourceunit 160 while supporting the lower edge of the display panel 110.

The extrusion bar 130 may be coupled to a side surface of the PCB 163such as being screw-coupled at the side surface 163 c of the PCB 163 onwhich the light source 161 is mounted. The PCB 163 may contact theextrusion bar 130 to transfer heat therebetween, but the invention isnot limited thereto. The extrusion bar 130 may define the fixing portion131 having a bar shape and the support portion 133 which extends fromthe fixing portion 131. In addition, the buffer 135 may be disposed onthe lower surface of the fixing portion 131. The adhesive 137 whichfixes the display panel 110 to the extrusion bar 130 may further bedisposed on the upper surface of the support portion 133.

The exemplary embodiment of the LCD device 100 according to theinvention may rapidly dissipate high-temperature heat generated by thelight source 161 outwards both through the PCB 163 having at least aportion thereof exposed external to the backlight unit, and through thebottom portion 191 of the lower frame 190 and the extrusion bar 130which are both coupled to the PCB 163.

In addition, the exemplary embodiment of the LCD device 100 according tothe invention may further include the heat dissipation tape 170 extendedto be attached to the upper surface 163 a of the PCB 163, to the otherside surface 163 d of the PCB 163 which is exposed externally, to theextrusion bar 130, and the like.

The heat dissipation tape 170 may increase emissivity of infrared lightgenerated on a surface of the PCB 163, thereby significantly enhancingradiant heat dissipation efficiency.

FIG. 6A is an exploded perspective view schematically illustratinganother exemplary embodiment of a backlight unit according to theinvention. FIG. 6B is a perspective view illustrating an assembled stateof the backlight unit of FIG. 6A. With regard to a descriptionpertaining to a light source unit in FIGS. 6A and 6B which is the sameas that of the light source unit 160 provided in FIGS. 5A and 5B, therepetitive description will be omitted.

Referring to FIGS. 6A and 6B, a PCB 163 may have a bar shape whichdefines an upper surface 163 a, a lower surface 163 b, and side surfaces163 c and 163 d of the PCB 163. At least one light source 161 may bemounted on one side surface 163 c side surfaces 163 c and 163 d of thePCB 163. Referring to FIGS. 6A and 6B, although an insulating layer isnot shown separate from a light source, the feature labeled 161 may beconsidered as representing an insulating layer within 161 and adjacentto the side surface 163 c of the PCB 163 so as to be disposed between alight source within 161 and the PCB 163.

The PCB 163 may be one of a metal printed circuit board (“MPCB”) and ametal core printed circuit board (“MCPCB”). A length of the PCB 163 maybe coupled to and extend along an edge of a bottom portion 191 of thelower frame 190 (refer to FIG. 1). In particular, the lower surface 163b of the PCB 163 and the bottom portion 191 of the lower frame 190 maybe coupled to each other such as by being screw-coupled to each other.

In addition, the exemplary embodiment of the backlight unit may furtherinclude an extrusion bar 130 coupled to the PCB 163 to be disposed abovethe light source 161, where the extrusion bar 130 also externallydissipates heat generated in the light source unit 160 while supportingthe lower edge of the display panel 110. The extrusion bar 130 may becoupled to the PCB 163 such as being screw-coupled to the upper surface163 a of the PCB 163.

Further, the exemplary embodiment of the backlight unit may furtherinclude a heat dissipation tape 170 attached to an externally exposedside surface 163 d of the PCB 163, to the extrusion bar 130, and thelike. While the heat dissipation tape 170 in FIG. 6B is illustratedexposing an upper surface of the fixing portion 131 of the extrusion bar130, the invention is not limited thereto. In an exemplary embodimentthe heat dissipation tape 170 may overlap an upper surface of the fixingportion 131 of the extrusion bar 130 such as illustrated in FIG. 5B.

FIG. 7 is a cross-sectional view schematically illustrating a path ofheat generated in a light source of an exemplary embodiment of abacklight unit according to the invention.

Referring to FIG. 7, a relatively large amount of heat generated by thelight source 161 when the light source 161 is driven may be initiallytransmitted to a first side surface 163 c (refer to FIGS. 5A and 6A) ofthe PCB 163 that includes or may be formed of a metal material. Arrowsoverlapping the light source 161 in FIG. 7 indicate transmission of heatfrom the light source to the PCB 163.

The heat initially transmitted to the PCB 163 may be relatively rapidlyand efficiently dissipated through a second side surface 163 d (refer toFIGS. 5A and 6A) of the PCB 163 externally exposed from the lower frame190. The heat dissipated through the second side surface 163 d of thePCB 163 may be transmitted through the heat-dissipating tape 170 on thesecond side surface 163 d of the PCB 163 externally exposed from thelower frame 190. If the heat-dissipating tape 170 is on the uppersurface 163 a (refer to FIGS. 5A and 6A) of the PCB 163, the heat mayalso be dissipated through the upper surface 163 a of the PCB 163 andthrough the heat-dissipating tape 170 on the upper surface 163 a of thePCB 163.

The heat initially transmitted through the first side surface 163 c ofthe PCB 163 may be relatively rapidly and efficiently dissipated througha body of the PCB 163 and back through the first side surface 163 c ofthe PCB 163 to the extrusion bar 130 which is coupled to the uppersurface 163 a or the first side surface 163 c of the PCB 163. If theheat-dissipating tape 170 is on the upper surface of the extrusion bar130, the heat may also be dissipated through the upper surface of theextrusion bar 130 and through the heat-dissipating tape 170 on the uppersurface of the extrusion bar 130.

The heat initially transmitted through the first side surface 163 c ofthe PCB 163 may be relatively rapidly and efficiently dissipated througha body of the PCB 163 and through a lower surface 163 b (refer to FIGS.5A and 6A) of the PCB 163 to the bottom portion 191 of the lower frame190 (refer to FIG. 1) which is coupled to the lower surface 163 b of thePCB 163.

As set forth above, according to one or more exemplary embodiments, thebacklight unit with one or more heat dissipating members and the LCDdevice including the same may enhance heat dissipation efficiency by ametal-material PCB having relatively high thermal conductivity andhaving a predetermined thickness, and by exposing the highly thermallyconductive PCB directly to an external environment relative to thebacklight unit.

In addition, the backlight unit with one or more heat dissipatingmembers and the LCD device including the same may enhance heatdissipation efficiency by thermally contacting the PCB, on which thelight source is mounted, to the metal frame (e.g., a lower frame, aextrusion bar, etc.) which accommodates the respective components of theLCD device therein. The PCB may be in direct contact with the metalframe, but the invention is not limited thereto.

Further, the backlight unit with one or more heat dissipating membersand the LCD device including the same may include the heat dissipationtape as a heat dissipating member, where the heat dissipation tape hasthe microcavity structure and the microcavity-structure heat dissipationtape is disposed on the externally exposed portion of the PCB on whichthe light source is mounted.

From the foregoing, it will be appreciated that various exemplaryembodiments in accordance with the present disclosure have beendescribed herein for purposes of illustration, and that variousmodifications may be made without departing from the scope and spirit ofthe present teachings. Accordingly, the various exemplary embodimentsdisclosed herein are not intended to be limiting of the true scope andspirit of the present teachings. Various features of the above describedand other exemplary embodiments can be mixed and matched in any manner,to produce further exemplary embodiments consistent with the invention.

What is claimed is:
 1. A backlight unit comprising: a light source whichgenerates light; a printed circuit board on which the light source ismounted; and a lower frame in which the light source and the printedcircuit board are accommodated, wherein the lower frame comprises: abottom portion having a planar shape; and a side wall portion bent froman edge of the bottom portion to extend therefrom, wherein the side wallportion defines an aperture at the edge of the bottom portion, theprinted circuit board is disposed at the aperture defined by the sidewall portion of the lower frame, and a portion of the printed circuitboard disposed at the aperture is exposed outside the backlight unit. 2.The backlight unit of claim 1, wherein the aperture has a substantiallysame planar area as that of a surface of the printed circuit board whichis disposed at the aperture.
 3. The backlight unit of claim 1, whereinthe light source is a light emitting diode.
 4. The backlight unit ofclaim 1, wherein the printed circuit board is one of a metal printedcircuit board and a metal core printed circuit board.
 5. The backlightunit of claim 1, wherein the printed circuit board includes at least oneof stainless steel, aluminum, an aluminum alloy, magnesium, a magnesiumalloy, copper, a copper alloy and an electro-galvanized steel sheet. 6.The backlight unit of claim 1, wherein the printed circuit boarddisposed at the aperture is coupled to the bottom portion and heat istransferred between the printed circuit board and the bottom portioncoupled to each other.
 7. The backlight unit of claim 6, wherein theprinted circuit board is screw-coupled to the bottom portion and theheat is transferred between the printed circuit board and the bottomportion screw-coupled to each other.
 8. The backlight unit of claim 1,further comprising a light source unit comprising therein: the lightsource which generates the light, the printed circuit board which isdisposed at the aperture, and an insulating layer between the lightsource and the printed circuit board.
 9. The backlight unit of claim 1,wherein the printed circuit board has a thickness in a range of about0.5 millimeter to about 3.0 millimeters.
 10. The backlight unit of claim1, further comprising a heat-dissipating extrusion bar coupled to theprinted circuit board which is disposed at the aperture, wherein heat istransferred between the heat-dissipating extrusion bar and the printedcircuit board coupled to each other, and the heat-dissipating extrusionbar coupled to the printed circuit board is disposed above the lightsource.
 11. The backlight unit of claim 10, wherein the heat-dissipatingextrusion bar is screw-coupled to the printed circuit board which isdisposed at the aperture and the heat is transferred between theheat-dissipating extrusion bar and the printed circuit boardscrew-coupled to each other.
 12. The backlight unit of claim 10, whereinthe heat-dissipating extrusion bar includes at least one of stainlesssteel, aluminum, an aluminum alloy, magnesium, a magnesium alloy,copper, a copper alloy and an electro-galvanized steel sheet.
 13. Thebacklight unit of claim 1, further comprising a heat-dissipating tapeattached to a surface of the printed circuit board which is disposed atthe aperture, the surface of the printed circuit board to which theheat-dissipating tape is attached being exposed outside the backlightunit.
 14. The backlight unit of claim 13, wherein the heat-dissipatingtape defines a microcavity structure.
 15. A liquid crystal displaydevice comprising: a display panel which displays an image using alight; and a backlight unit which provides the light to the displaypanel, the backlight unit comprising: a light source which generates andprovides the light; a printed circuit board on which the light source ismounted; and a lower frame in which the display panel, the light sourceand the printed circuit board are accommodated, wherein the lower framecomprises: a bottom portion having a planar shape; and a side wallportion bent from an edge of the bottom portion to extend therefrom,wherein the side wall portion defines an aperture at the edge of thebottom portion, the printed circuit board is disposed at the aperturedefined by the side wall portion of the lower frame, and a portion ofthe printed circuit board disposed at the aperture is exposed outsidethe backlight unit.
 16. The liquid crystal display device of claim 15,wherein the aperture has a substantially same planar area as that of asurface of the printed circuit board which is disposed at the aperture.17. The liquid crystal display device of claim 15, wherein the printedcircuit board which is disposed at the aperture is coupled to the bottomportion and heat is transferred between the printed circuit board andthe bottom portion coupled to each other.
 18. The liquid crystal displaydevice of claim 15, further comprising a heat-dissipating extrusion barcoupled to the printed circuit board which is disposed at the aperture,wherein heat is transferred between the heat-dissipating extrusion barand the printed circuit board coupled to each other, and theheat-dissipating extrusion bar coupled to the printed circuit board isdisposed above the light source.
 19. The liquid crystal display deviceof claim 18, wherein the heat-dissipating extrusion bar defines asupport portion thereof to support the display panel thereon.
 20. Theliquid crystal display device of claim 15, further comprising aheat-dissipating tape attached to a surface of the printed circuit boardwhich is disposed at the aperture, the surface of the printed circuitboard to which the heat-dissipating tape is attached being exposedoutside the backlight unit.